Countercurrent contactor



Feb. 4, 1936. Y

J. ROBINSON COUNTER CURRENT CONTACTOR Filed Aug. 12, 1953 4 HNVENTOR'Jack, Robmaon BY M-Bwmw,

ATI'QRNEY @tente re. a we weasel communes-near oonraeron Jackltphilnsoh, Wood River, 111111., assignor ta Standard Uil illompany,(Chicago, lllilt.9 a cor poration of llindiana Application August 12,was, serial its. teases e creams. (oi. ite -it) This invention relatesto apparatus for the countercurrent contacting of two fluids,particularly two liquids. It is especially adapted to the extraction ofpetroleum fractions, for instance alubricating oil stockfwith aselective solvent or solvent mixture.

It is an object of my invention to provide an apparatus of the abovetype which will accomplish eiiieient equilibrium contacting of the twofluids in each of a plurality of stages. Another object is to provide anapparatus in which this can be accomplished together with the attainmentof maximum throughput. Other and more detailed objects will becomeapparent as the description of my invention proceeds.

My invention will now be described in detail with reference to thepreferred embodiment shown in the accompanying drawing in which Figure 1is an elevation of my countercurrent contactor partly in section; and

Figure 2 is a partial elevation taken along the line 2--2 of Figure 1.

Referring now to the drawing in more detail, a generally horizontalcasing l I, which may suitably be of the approximate cross-section shownin' Figure 2, rests on supports I2 and is divided into two endcompartments I3 and a plurality of intermediate compartments l4 by meansof is also provided with a fluid inlet 22 equipped with a valve 23 andthe left hand end compartment I3 is equipped with a fluid inlet 24 whichis provided in turn with a valve 25. Inlet 22 is preferably, but notnecessarily, located near the top of right hand end compartment I 3andinlet 24 is preferably, but not necessarily, located near the bottomof left hand end compartment l3.

Intermediate compartments l4 are provided with downwardly projectingbailies 26 which may suitably be segmental in form and are preferablyapproximately perpendicularly disposed with respectto the axis of casingll. Baflies 26 may be centrally'locatedin compartments l4 but arepreferably located somewhat nearer to the right hand end of thecompartment As will be explained later this may be referred to as the upstream end of the compartment. Compartments it arelikewise provided withupwardly project= ing baflies 2'! which may suitably be segmental inshape and are'preferably approximately per-=- i'pendicularly disposedwith respect to the axis of casing ll. Baflies 2'1! are preferablylocated somewhat closer to the left or upstream end oi the compartmentthan to the other end.

Casing M or a portion of it is traversed by shafts 23 and 29 which arepreferably located in vertical alignment with each" other and parallelto the axis of easing ii. Shaft 22, in the form shown in Figure l, isjournaled at 30, $0,

and 32 and is driven from drive shaft tit by means of a pair of variablepulleys 3t and a belt 35. Similarly, shaft 29 is journaled at 36, illand 38 and is driven through drive shaft 32 by means of a pair ofvariable pulleys 39 and the belt til. Drive shaft 33 is in turn driventhrough pulleys 4i, belt 42 and variable speed reducer 43 by means ofmotor 4t. Variable speed reducer 43 is controlled by means of lever 25.It is thus possible to drive shafts 28 and 29 at a wide range ofselected rates of rotation. Furthermore, by means of pulleys 34 and/orpulleys 39 the rates of rotation of the two shafts can be independentlyvaried. It is also possible to change the direction and location ofeither of the shafts by closing belt 35 or belt 40.

Bafliles 26 divide the upper portions or intermediate compartments i4into upper upstream zones 46 and'upper downstream zones 41. Shaft 28carries paddle wheels at which are located within or project into upperupstreamzones 46. Similarly, baflies 21 divide the lower portions ofintermediate compartments l4'into lower upstream zones 49 and lowerdownstream zones 50. Paddle wheels 5| are carried by shaft 29 within orprojecting into lower upstream zones 49. The paths 52 of the tips ofpaddle wheels 48, as shown in Figure 2, project upwardly to points abovethe lower edges of baflles 26 but below the upper edges of baflles l5.Similarly the paths 53-of the tips of paddle wheels 5| project at theirlowest points 4 below the upper edges of baiiles 21 but above the loweredges of baffles I 5. The reason for this will become apparent later inthe description. Shafts 28 and 29 should be so located that paddlewheels 48 and 5| will fulfill the foregoing re- 5 These gas vents areconnected to manifold 55 by means of valves 56. Manifold 55 is alsoprovided with a master valve 51.

Having described my countercurrent contacting apparatus I will nowproceed to outline the processes for which it is adapted and itsfunctional advantages with respect to those processes. The apparatus canbe utilized for the contacting of any twofluids, but it is particularlyadapted to contacting two liquids which are not completely miscible witheach other under the prevailing operating conditions and which aresubstantially different in specific gravity.

The liquid of lower specific gravity is intro duced through inlet 22 bymeans of valve 23 and flows through casing ll past and around thevarious baiiies l5 and 26 and finally past battle 58 up into extension19 and out through outlet 20 and valve 2|. Simultaneously the liquid ofhigher specific gravity is introduced through inlet 24 by means of valve25 and fiows along the bottom of easing Ii past the various bafiies i5and 21, finally past baffle 59, into downward extension [6 and then outof the apparatus through outlet [1 and valve l8. While the two liquidsare thus being fiowed through the apparatus in countercurrent contactwith each other, shafts 28 and 29 are rotated by means of motor M, etc.at optimum speeds to be determined as hereinafter described. Paddlewheels 48 and 5! attached to shafts 28 and 29 respectively are rotatedthereby. The rotation of these blades tends to promote emulsificationbetween the two liquids being contacted. This is highly desirable sinceit insures intimate contact and the attainment of equilibrium betweenthe two liquids. Nevertheless, it is desirable that the emulsion afterbeing formed be broken so that the unemulsified liquid can pass on tothe next stage of the process and again to undergo emulsification.

My invention makes this desirable result possible and in effect makeseach of compartments ll a distinct stage wherein equilibrium is obtainedand the two liquids pass on in opposite directions to the next stages.

The method by which this is accomplished will be described withparticular reference to the right hand one of compartments H which maybe taken as typical. The lighter liquid entering the apparatus throughinlet 22 passes over the top of the right hand one of baffies I5 andenters upper upstream zone 46 wherein it is vigorously agitated bypaddle wheel 48. This agitation together with the agitation provided bypaddle wheel 5| located in the lower left hand portion of compartment 14produces a central zone of emulsified material wherein the two liquidsare in intimate contact within each other. A portion of this emulsifiedmaterial passes around the lower end of baffle 26 and into the upperdownstream zone 41 wherein there is no agitation and the light liquidwhich has been in contact with the heavy liquid settles out and passesover the top of the next bafiie 15 into the next compartment.Simultaneously heavy liquid enters compartment H at the lower left andcomes into lower upstream zone 49 wherein it is vigorously agitated bymeans of paddle wheel 5|. A por tion of the emulsified material passesover the top of bafiie 21 and the lower liquid settles out in the lowerdownstream zone 50 and then passes out of the compartment at the lowerright. Both the light and heavy liquids thus first enter a vigorousagitation zone and are contacted with the other liquid and then enter arelatively quiescent zone in which they settle out and pass on in thenext compartment. The quiescent zones should preferably be rather largerthan the agitation zones.

The approximate preferred interfacial levels between each of the liquidsand the emulsification zone are shown by dashed lines in Figure 1. Itwill be understood, of course, that these lines are approximate onlysince in many cases the emulsified layer will gradually taper off intothe unemulsified layer. In the right hand end compartment I3 interfaciallevel should be relatively high in order to permit the settling out ofentrained light liquid from the heavy liquid being withdrawn throughoutlet 11. Similarly interfacial level 60a in left hand end compartmentl3 should be relatively low so as to permit the settling out ofentrained heavy liquid from the light liquid being withdrawn throughoutlet 20. Level 50a must in general be above level 66 so that thehydrostatic head necessary to secure flow through the apparatus can besecured. Interfacial level 8! in upper upstream zone 16 represents theapproximate interface between the light liquid and the emulsifiedmaterial. level should preferably meet bafliel5 near the top thereof.After flowing around baiile 25 into relatively quiescent zone 47, thelevel '52 between. the light liquid and the emulsified material will besomewhat lower than level 6i due to the absence of agitation. Similarconsiderations apply to levels 63 and 64 representing the approximateinterfaces between the heavier liquid and the emulsified material.

These optimum results can be obtained by com trol of the rates ofrotation of shafts 28 and 29, by control of valves l8, 2!, 23, and 25and if desired by the use of interracial liquid level controls (notshown) located in one or both of end compartments i3 cooperating withone or more of valves l8, 2 l, 23, and 25. In the preferred method aninterracial liquid level control is used in one of end compartments I3in cooperation with a pressure control valve located in the outlet fromthe opposite end compartment.

The provision of gas vents 54 is of great importance when contacting twoliquids, since the accumulation of air, vapors, etc. in the upperportions of the various compartments, particularly immediately on theupstream sides of baiiies 28 may otherwise interfere seriously with theoperation of the apparatus.

While paddle wheels 48 and 5| may suitably be formed of fiat blades,cups, etc. facing in the direction of rotation, it is sometimesdesirable to slope them slightly so as to help propel the two liquids intheir respective downstream directions. This tends to increase thethroughput of the device. Too great a propulsion must be avoidedhowever, since it interferes with the attainment of equilibrium in eachstage. It is also sometimes desirable to use more than two paddles ineach of compartments ll. The paddles should, however, be confinedlargely to zones 46 and 49.

It is a matter of considerable importance that the angle at which casingl l is tilted to the horizontal be carefully selected. If this angle istoo small the rate of flow through my apparatus will be very' small andthe aforementioned relationships between the various interfacial levelscannot be obtained. On the other hand, there is an upper limit, angleslarger than which cannot be used without sacrifice of efliciency oroperability. Angles from about 5 to about 30 can be used although anglesfrom about 8 to about 20 are This aoaaooi preferable. The term"generally horizontal ap plied herein to casing l l covers angles from 0to or to the horizontal.

While my process and apparatus can be used for contacting any two fluidsand particularly for the contacting of any two non-miscible liquidsdiffering substantially in specific gravity, it is peculiarly adapted tocountercurrent extraction of petroleum fractions and more particularlyto countercurrent extraction of lubricating oil stocks. In a preferredembodiment the material introduced through inlet 22 and withdrawnthrough outlet 2t] is a lubricating oil stock, and the materialintroduced through inlet 2d and withdrawn through outlet W is aselective solvent such as dichlorethyl ether, nitrobenzene, cresylicacid, phenol, sulfur dioxide or a mixture of sulfur dioxide and benzol.

. the unemulsifled material tends to rotate with the til) paddles withthe result that it is carried under or over one end of the edges ofbattles it: or til with consequent short-circuiting. In other words, aportion of the material passes from agitation zone it to quiescent zonedli or from agitation zone iii to quiescent zone till without havingbeen emulsified. Ihis can be remedied by dis= placing battles 2t and/or2i! in the direction of the rotation of the corresponding paddle wheelsso that thisVshort-circuiting will not occur. Alter-=- natively thebafiies can be extended on the edge over or under which theunernulsified liquid passes so that short-circuiting will be prevented.

While I have described my invention in corn nection with a specificembodiment thereof, 1 do not wish to be limited thereby but only to thescope of the appended claims in which if have set forth the novelfeatures of my invention.

I claim:

1. Apparatus for the countercurrent contacting of two comprising agenerally horizontal casing, a plurality of bailies partially dividingsaid casing into a plurality of compartments, and in dependent agitationmeans located in and corniined to diagonally disposed portions of saidcompartments.

2. Apparatus for the countercurrent contacting of two fluids, comprisinga generally horizontal casing, a plurality of baflles partially dividingsaid casing into a plurality of compartments, baffles dividing the upperportions of said compartments into two upper zones, bafiles dividing thelower portions of said compartments into two lower zones, agitationmeans located in and confined to one of said upper zones and agitationmeans located in and confined to one of said lower zones diagonallydisposecl'with respect to said last mentioned upper zone.

3. Apparatus for the countercurrent contacting of two fluids, comprisinga generally horizontal casing, a plurality of bailles disposedapproximately perpendicularly to the axis of said casing and dividingsaid casing into'two end compartmentsand a plurality of intermediatecompartments, a plurality of bafiies extending from the top g f saideasing into said intermediate compartments and dividing saidintermediate compart-' ment into two upper zones, a plurality of bafllesextending from ,the bottom of said casing into said intermediatecompartments and dividing said intermediate compartmentsinto twp lowerzones, a shaft traversing said upper zones, a second shaft traversingsaid lower zones, means for roe tating said shafts, agitation meanscarried by said first-mentioned shaft within at least one of said upperzones, agitation means carried by said second shaft within at least oneof said lower zones diagonally disposed with respect to saidlast-mentioned upper zone, a fluid inlet located in each of said endcompartments and a fluid outlet located in each of said endcompartments.

l. Apparatus for countercurrent contacting comprising a generallyhorizontal casing, a plurality of bafiles disposed approximatelyperpendicularly to the axis of said casing and dividing said easing intotwo end compartments and a plurality of intermediate compartments, aplurality of battles extending from the top of said casing into each ofsaid intermediate compartments and dividing each of said intermediatecompartments into a downstream upper zone and an upstream upper zone, aplurality of baffles extending from the bottom of said easing into eachof said inter mediate compartments and dividing each of saidintermediate compartments into a downstream traversing said upper zones,a second shaft traversing said lower zones, means for rotating saidshafts, means for controlling the rates of rotation of said shafts,agitation means carried by said first-mentioned shaft Within saidupstream upper zones, agitation means carried by said second shaftwithin said upstream lower zones, a fluid inlet located in each of saidend compartments and a fluid outlet located in each of said endcompartments.

5. Apparatus for countcrcurrent contacting comprising a generallyhorizontal casing, a plu rality of baffles disposed approximatelyperpendicularly to ,the axis of said casing and dividing said casinginto two and compartments and a plurality of intermediate compartments,a plurality of baffles extending from the top of said casing into eachof said intermediate compartments and dividing each of said intermediatecompartments into a downstream upper zone and an upstream upper zone, aplurality of baflles extending from the bottom of said easing into each0 of said intermediate compartments and dividing each of saidintermediate compartments into a downstream lower zone and anupstreamlower zone, a shaft traversing said upper zones, a second shafttraversing said lower zones, means for rotating said shafts, means forcontrolling the rates of rotation of said shafts, means locatedsubstantially within said upstream upper zones and carried by saidfirst-mentioned shaft for agitating the material in the upper portion ofsaid casing and propelling it downstream, means lower zone and anupstream lower zone, a shaft iii) located substantially within saidupstream lower' 6. Apparatus for countercurrent contacting comprising agenerally horizontal casing, a plurality' of bafiles disposedapproximately perpendicularly to the axis of said casing and dividingsaid casing into two end compartments and a plurality of intermediatecompartments, upper passages located near the tops of said bafllesconnecting each adjacent pair of said compartments, lower passageslocated near the bottoms of said baffles connecting each adjacent pairof said compartments, a plurality of baflles extending from the top ofsaid casing into each of said intermediate compartments and dividingeach of said intermediate compartments into a downstream upper zone andan upstream upper zone, a plurality of baffios extending from the bottomof said casing into each of said intermediate compartments and dividingeach of said intermediate compartments into a downstream lower zone andan upstream lower zone, a shaft traversing said upper zone, agitationmeans carried by said shaft substantially within said upstream upperzones and extending upward to a maximum height above the lower edges ofsaid second-'mentioned baiiies and below said upper passages, a secondshaft traversing said lower zones, agitation means carried by saidsecond shaft substantially within said upstream lower zones andextending downward to a maximum depth below the upper edges of saidthird-mentioned bafiles and above said lower passages, means forrotating said shafts, means for controlling the rate of rotation of saidfirst-mentioned shaft, means for controlling the rate of rotation ofsaid second shaft, a fluid inlet located in each of said endcompartments and a fluid outlet located in each of said endcompartments'.

7. Apparatus for the countercurrent contacting of two liquidsincompletely miscible with each other and differing substantially fromeach other in specific gravity, comprising a casing inclined to thehorizontal, a plurality of baflles partially dividing said casing into aplurality of compartments, and independent agitation means located inand confined to diagonally disposed portions of said compartments.

8. Apparatus for the countercurrent contacting of two liquidsincompletely miscible with. each other and differing substantially fromeach other in specific gravity, comprising a casing inclined to thehorizontal, a plurality of baffles disposed approximatelyperpendicularly to the axis of said casing and dividing said casing intotwo end compartments and a plurality of intermediate compartments, aplurality of baffles extending from the top of said casing into saidintermediate compartments and dividing said intermediate compartmentinto/two upper zones, a plurality of baflies extending from the bottomof said casing into said intermediate compartments and dividing saidintermediate compartments into two lower zones, a shaft traversing saidupper zones, a second shaft traversing said lower zones, means forrotating said shafts, agitation means carried by said first-mentionedshaft within at least one of said upper zones, agitation means carriedby said second shaft within at least one of said lower zones diagonallydisposed with respect to said last-mentioned upper zone, a liquid inletlocated in each of said end compartments and a. liquid outlet located ineach of said end compartments.

9. Apparatus for the countercurrent contacting of two liquidsincompletely miscible with each other and differing substantially fromeach other in specific gravity comprising a casing inclined to thehorizontal, a plurality of baffles disposed approximatelyperpendicularly to the axis of said casing and dividing said easing intotwo end compartments and a plurality of intermediate compartments, aplurality of baiiies extending from the top of said casing into each ofsaid intermediate compartments and dividing each of said intermediatecompartment s into a downstream upper zone and an upstream upper zone, aplurality of baffles extending from the bottom of said easing into eachof said intermediate compartments and dividing each of said intermediatecompartments into a downstream lower zone and an upstream lower zone, ashaft traversing said upper zones, a second shaft traversing said lowerzones, means for rotating said shafts, means for controlling the ratesof rotation of said shafts, means located substantially within saidupstream upper zones and carried by said firstmentioned shaft foragitating the material in the upper portion of said casing andpropelling it downstream, means located substantially within saidupstream lower zones and carried by said second shaft for agitating thematerial in the lower portion of said casing and propelling itdownstream in a direction opposed to the downstream direction of thematerial in the upper portion of said casing, a fluid inlet located ineach of said end compartments and a fluid outlet located in each of saidend compartments.

JACK ROBINSON.

